Signal significance in the presence of systematic and statistical uncertainties

The incorporation of uncertainties to calculations of signal significance in planned experiments is an actual task. We present a procedure of taking into account the effects of one sided systematic errors related to non-exact knowledge of signal and background cross sections on the discovery potential of an experiments. A method of a treatment of statistical errors of the expected signal and background rates is proposed. The interrelation between Gamma- and Poisson distributions is demonstrated. (author)